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P91 and P92 steels are widely used in nuclear and thermal power plant's high-temperature (650–700 °C) operating components. The welding procedure, base plate composition, filler material composition, and post-weld heat treatment (PWHT) significantly affect the metallurgical characterization of weldments at room temperature. This work focuses on joining P91 and P92 steel by the TIG welding with filler ER90S-B9. The study analyzes the materialization of coarse-grained HAZ (CGHAZ), inter-critical HAZ (ICHAZ), and fine grained HAZ (FGHAZ) under welded and PWHT. PWHT was conducted at 840 °C for 2, 4 and 6h. An optical microscopic (OM) scanning electron microscope (SEM) was employed to characterize the welded and PWHT samples. It was perceived that the tensile strength of PWHT increased as the heat treatment times increased from 2 to 6 h, while the hardness value decreased accordingly. The maximum tensile strength (594.71 MPa) was observed in PWHT_6 h, while the minimum tensile strength (537.52 MPa) was perceived in the as-welded sample. The PWHT_6h reveals the minimum hardness values (271.12 HV) at the fusion zone among all the conditions. The WFZ consisted of an untampered lath martensitic grain structure, demonstrating an average hardness value of 314.15 HV in the PWHT_2h condition. The hardness value in CGHAZ samples for as-welded, PWHT_2h, PWHT_4h, and PWHT_6h was observed at 456.85, 436.81, 368.63, and 327.41 HV, respectively. [ABSTRACT FROM AUTHOR]

Recycling crushed clay bricks (CCB) in concrete is a sustainable and cost-effective process. Huge quantities of crushed clay bricks waste cause many serious environmental problems around the world. To deal with this problem, crushed bricks were recycled in the concrete industry as an alternative to natural resources, and the brick powder was reused as a partial replacement for cement. The objective of this paper is to study the effect of crushed clay bricks on the characteristics of concrete. 7 concrete mixtures containing coarse crushed brick aggregate (CCBA) and fine crushed brick aggregate (FCBA) were prepared as a complete substitute for sand and dolomite, respectively. Clay brick powder (CBP) and silica fume were used as a partial substitute for cement by 5%, 10%, and 15% of its weight. The water-to-cement ratio was 0.35. For comparison, a control mixture was prepared. Various tests were conducted to evaluate the performance of concrete. The results showed that the workability of the different mixtures containing CCB decreased compared to that of the reference mixture. The compressive strength values of mixtures containing CCBA had a clear decrease compared to the reference mix at 7, 28, and 56 days of curing. The modulus of rupture results had the same path as compressive strength results. The thermal conductivity coefficient for mixtures including CCBA decreased compared to the control mix. Scanning Electron Microscope images indicated crystals of calcium silicate hydrate because of the pozzolanic interaction between the brick powder and the fine crushed clay bricks with calcium hydroxide. [ABSTRACT FROM AUTHOR]

In order to study the effect of the preparation process on the microstructure and mechanical properties of metal hollow sphere composites (MHSCs), they were fabricated using different preparation processes (different holding times) by a pressure casting method. The physical parameters of the MHSCs were measured using a direct measurement method, and the phases and microstructure of the MHSCs were observed using an X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and transmission electron microscope (TEM). Moreover, the mechanical properties of MHSCs were analyzed by a Zwick/Roell Z2.5 microhardness tester and a universal testing machine. The microscopic morphology and composition analysis results showed that the microstructures of MHSCs varied by holding time, while the mechanical properties test results implied that the microhardness of the transition layer and the matrix increased with the extension of the holding time. However, the MHSCs held for 10 min exhibited the best compression performance. These observations indicated that the compressive properties of MHSCs were mainly dependent on the transition layer and the matrix, excluding the influence of metal hollow spheres, and that the transition layer had a significant impact on the compression performance of MHSCs. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of Co contents on the structure and cavitation erosion property, NiTiAlCrCoxN films were prepared by the magnetron sputtering system. The X-ray diffractometer (XRD), the scanning electron microscope (SEM) and the energy dispersive spectrometer (EDS) were used to characterize the structure and morphology of the films. The nanoindenter and the scratch tester were used to analyze the mechanical properties of the films. Cavitation erosion experiments were carried out by the ultrasonic vibration cavitation machine. The results show that NiTiAlCrCoxN films with different Co contents have a simple face-centered cubic (FCC) structure and show a preferred orientation on the (200) crystal plane. The diffraction angle on the (200) crystal plane decreases and the interplanar spacing increases with the increase in Co content in NiTiAlCrCoxN films. NiTiAlCrCoxN films exhibit a typical columnar crystalline structure. With the increase in Co content, the nanohardness of the films increases and the elastic modulus of the films decreases, while the mass loss of cavitation erosion monotonously increases except for the film with a 1.2 Co molar ratio. The NiTiAlCrCo1.4N film has a minimum hardness of 13.264 GPa, a maximum elastic modulus of 253.22 GPa and a minimum mass loss of 0.72 mg in the cavitation erosion experiment. The NiTiAlCrCo1.4N film exhibits the best cavitation corrosion resistance because the addition of the Co element enhances the solid solution strengthening effect and the NiTiAlCrCox1.4N film with the biggest elastic modulus has better elasticity to reduce the micro jet impact. [ABSTRACT FROM AUTHOR]

In this work, microporous MgO–Al2O3 refractory aggregates were prepared with Mg(OH)2 and Al(OH)3 via the in situ decomposition synthesis method. The effect of Al(OH)3 addition on the microstructure and properties of microporous MgO–Al2O3 refractory aggregates was investigated with scanning electron microscope and mercury intrusion porosimetry. The results indicated that the improved green density of the samples and the reaction sintering accelerated the mass transport rate with adding Al(OH)3 from 0 to 4.0 wt%. Besides, a small amount of Al3+ diffused into porous MgO particles, accelerating the merging and growth of nanopores in the porous MgO particles. The intra‐particle pore size and the densification degree of microparticles were increased, and thus the strength of the samples was improved. Due to the formation of Kirkendall voids by interdiffusion of Mg2+ and Al3+, the inter‐particle pore size increased. Adding Al(OH)3 from 4.0 to 17.6 wt%, the Kirkendall voids weakened the mass transport rate and improved the inter‐particle pore size. The merging and growth of nanopores in the MgO particles were limited, resulting in the reduced intra‐particle pore size and increased intra‐particle pore number. The densification degree of microparticles was reduced, and thus the strength of the samples decreased. At the Al(OH)3 addition of 4.0 wt%, microporous MgO–Al2O3 refractory aggregates had the best comprehensive properties, a bulk density of 2.48 g/cm3, an apparent porosity of 29.4%, a median pore size of 1.6 μm with 42.2 vol% nanopores and the thermal conductivity of 4.0 W/(m K). [ABSTRACT FROM AUTHOR]

This study investigates the correlation between coercivity (Hc), grain size (d), and dislocation density in the Permimphy alloy (Fe–80%Ni–6%Mo). The samples used in this study were subjected to varying levels of applied strain through processing by high-pressure torsion. The microstructure and the magnetic coercivity were analyzed using a scanning electron microscope, electron backscatter diffraction and vibrating sample magnetometry. The grain size of the samples varied from 30 to 190 nm. This study demonstrated a strong correlation between Hc and microhardness when d > 3 µm. The results show that the coercivity of the Permimphy alloy follows an inverse V-shape with respect to grain size. The coercivity of the samples decreased despite increasing the dislocation density and the hardness when d < 3 µm. This phenomenon is attributed to the ferromagnetic exchange interaction across multiple grains and leads to the alignment of magnetic moments. [ABSTRACT FROM AUTHOR]

The harsh service environment of aeroengine hot-end components requires superalloys possessing excellent antioxidant properties. This study investigated the effect of pre-strain on the oxidation behavior of polycrystalline Ni3Al-based superalloys. The growth behaviors of oxidation products were analyzed by scanning electron microscope, transmission electron microscope, X-ray Photoelectron Spectroscopy and Raman spectroscopy. The results indicated that the 5% pre-strained alloys exhibited lower mass gain, shallower oxidation depth and more compact oxide film structures compared to the original alloy. This is mainly attributed to the formation of rapid diffusion paths for Al atoms diffusing to the surface under 5% pre-strain, which promotes the faster formation of protective Al2O3 film while continuing to increase the pre-strain to 25% results in less protective transient oxidation behavior being aggravated due to the increase in dislocation density within the alloy, which prevents the timely formation of the protective Al2O3 film, resulting in uneven oxidation behavior on the alloy. [ABSTRACT FROM AUTHOR]

This study examines the impact of the size and wt.% of reinforcement particles on the wear characteristics of Al2021 alloy composites. Composites of Al2021 reinforced with B4C particles of varied sizes (45 and 90 microns) were synthesised utilising a unique two-stage stir cast technique. The composites were primed with B4Cc content of 5 and 10 wt.%. The microstructural characterisation of Al2021 alloy with B4C composites of 45 and 90-micron sizes was conducted using Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS). In addition, wear and worn morphology tests were conducted to examine the impact of particle size on the behaviour of Al2021 alloy. Furthermore, another set of wear studies was conducted with the load maintained at 40N and the sliding speeds changed from 100 to 400 rpm. The microstructural analysis disclosed that the particles in the Al2021 alloy were evenly distributed, and the presence of elements was verified using EDS spectra. Using B4C particles of different sizes enhanced wear characteristics with resistance to wear. The load and the speed affected the wear behaviour of every prepared sample. The morphological analysis of the worn samples recognised multiple wear mechanisms. [ABSTRACT FROM AUTHOR]

In this study, La2Zr2O7, Yb2O3 and Gd2O3-doped La 1. 4 (Gd, Yb) 0. 6 Zr2O7 thermal barrier coatings have been manufactured from the crystalline and amorphous feedstock by plasma spraying. The thickness of the bond coat is 100±25 μ m and the thickness of the top coat is 250±25 μ m. Thermal shock tests were carried out in furnace temperature of 1200∘C. The thermal shock tests indicate that lifetime of the La 1. 4 Gd 0. 6 Zr2O7 coating has 55 cycles which is the highest thermal shock lifetime compared to other coatings in this study. The type of feedstock, amorphous or crystalline, strongly affects the thermal shock lifetime of La2Zr2O7 coatings. Coating damage after thermal shock tests was investigated using scanning electron microscope to observe the microstructure and X-ray diffraction techniques to analyze the phase composition. The failure of coatings is mainly in consequence of the accumulation of stress between bond coat–ceramic coat interface due to thermal expansion coefficient differences and thermally grown oxide layer formation during thermal shock cycling tests. [ABSTRACT FROM AUTHOR]

In this article, the effect of Ce element on the microstructure and mechanical properties was studied by Ce addition to the hot‐formed steel. Scanning electron microscope and energy dispersive spectrometer (SEM‐EDS) was used to analyze the improvement effect of Ce on inclusions and the effect of inclusions on fracture behavior; Electron back scattering diffractometer (EBSD) was used to analyze the refinement and strengthening effect of Ce on martensitic grains; transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) was used to analyze the microstructure strengthening effect and microalloying effect of solid solution Ce in hot‐formed steel. Through a systematic analysis of mechanical properties and microstructure, the mechanism of Ce enhances the strength and elongation of hot‐formed steel was clarified. Besides, this work provides a research basis for further improving the safety and machinability of hot‐formed steel. [ABSTRACT FROM AUTHOR]

Bi(2/3)‐xSmxCu3Ti4O12 (BSCTO x = 0.05, 0.10, and 0.20) ceramics are synthesized using semi‐wet technique and an extensive investigation into their structural, morphological, and elemental properties, alongside dielectric and impedance behaviors, is meticulously carried out. X‐ray powder diffraction analysis unequivocally confirmed the formation of a monophasic BCTO cubic phase without any discernible secondary phases. and the crystallite size of the BSCTO ceramic, obtained by X‐ray diffraction using Debye Scherrer formula, range from 62 to 81 nm. Rietveld analysis reveals that ceramics have a body centered cubic structure with space group Im‐3. The Scanning electron microscope image displays the dense microstructure of the ceramics, while EDX analysis unveils the elemental composition of resulting products. Doping with Sm3+ induced a notable reduction in grain size, as observed through Scanning electron microscope and Atomic Force Microscope analyses, indicating Sm3+ hindered grain growth during sintering, potentially resulting in reduced dielectric constant (ε′). Dielectric constant and dielectric loss of the composition (x = 0.2) are found to be ≈$ \approx $152 and 0.04, respectively at room temperature (1 kHz). Impedance characteristics revealed a substantial increase in grain boundary resistance, leading to improved dielectric loss. The AC conductivity of BSCTO ceramics exhibited a frequency‐dependent increase satisfying to Johncher's power law. [ABSTRACT FROM AUTHOR]

As a countermeasure to the problem of brittleness of seawater sea sand concrete (SSC), volumetric admixture of glass fiber (GF) and polyvinyl alcohol (PVA) fiber was used as variable, the corresponding specimens were prepared, and the cube compressive strength, splitting tensile strength, axial compressive strength, and elastic modulus were tested. The microstructure of fiber reinforced seawater sea sand concrete was analyzed by scanning electron microscope (SEM) scanning and energy dispersive spectroscopy (EDS) dot scanning, and a model was established based on the grey system theory. The research results show that the fiber can effectively reduce the formation of cracks, leading to a ductile failure of the specimen. In general, the mechanical properties of mixed fiber were improved better than that of single fiber, and the hybrid ratio 2:1 brings a improvement of 24. 2% and 38. 8% for the compressive strength and splitting tensile strength, respectively. The hybrid ratio of 1:1 increases the axial compressive strength and elastic modulus by 34. 5% and 15. 5%. It was observed by SEM and EDS that fiber incorporation could densify the matrix, while the main disadvantage of SSC was that the salt crystallization generated by corrosive ions and swelling substances weakened the bond between aggregate and mortar, resulting in defects of interfacial transition zone (ITZ) . The established NSGM(1, 3) model has a high accuracy, the accuracy reaches class II and conforms to the long-term prediction, which provides a favorable basis for the study of the strength evolution of fiber reinforced seawater sea sand concrete. [ABSTRACT FROM AUTHOR]

Micron‐sized graphite particles additions to Al2011 alloy were investigated to know their impact on mechanical properties. The stir cast method was used to manufacture the Al2011 alloy with 2 and 4 wt% of graphite particles reinforced composites. The microstructural analysis and mechanical properties of the synthesized composites were tested. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) spectrums were used to characterize the microstructure of the samples that were obtained from the casting. SEM micrographs indicated the homogeneous distribution of particles and the EDS patterns confirmed the presence of graphite particles. Al2011 alloy hardness was decreased with the addition of graphite particles. Further, with the addition of 2 and 4 wt% of graphite particles in the Al2011 alloy, the ultimate tensile and yield strengths of composites were increased with increase in elongation. SEM micrographs of tensile fractured surfaces were used to study the various fractured behaviors in the Al2011 alloy‐graphite composites. [ABSTRACT FROM AUTHOR]

Sintered foils are currently being considered as a promising material for anode foils in capacitors due to their high specific capacitance and anti-buckling performance, which meet the requirements for capacitor winding. In this article, sintered foils with added starch were produced using a protective atmosphere sintering process. The effect of starch addition in the range of 0–50 vol% on the specific capacitance and anti-buckling performance of the sintered foils was evaluated. Scanning electron microscope (SEM) analysis confirmed the formation of the pores in the sintered foils due to the addition of starch. These pores play a crucial role in improving the specific capacitance and enhancing the anti-buckling performance of the sintered foils. However, excessive amounts of starch can have a negative impact on the specific capacitance of the sintered foils which initially decreased, then increased, and finally decreased with increasing starch content. On the other hand, the anti-buckling performance increased with increasing starch content. At 30 vol% starch addition, a high specific capacitance of 0.886 μF/cm2 and an anti-buckling performance of more than 120 times were obtained, meeting the requirements for anode foils in aluminum electrolytic capacitors. The specific capacitance of the sintered foils was predicted using the close-packed packing model, which can help establish a powder metallurgy method for preparing anode foil materials with high specific capacitance and anti-buckling performance for aluminum electrolytic capacitors. [ABSTRACT FROM AUTHOR]

Due to the poor activation performance and kinetics of Ti50V25Cr25 alloys, the element Zr was added to improve the phase structure of the alloy and achieve a high-performance hydrogen storage alloy. The Ti50−xV25Cr25Zrx (x = 0, 5, 7, and 9) system alloys were prepared by arc melting. The alloys were analyzed using an X-ray diffractometer (XRD), scanning electron microscope (SEM), and differential scanning calorimeter (DSC). The hydrogen storage capabilities of the alloys were also obtained by the Sievert volumetric method. The results indicated that the alloy with Zr added had a combination of the C15 Laves phase and the BCC phase, whereas the Zr-free alloy had a BCC single phase. The partial replacement of Zr with Ti resulted in an increase in the lattice parameters of the main phase. The hydrogen storage kinetic performance and activation of the alloys both significantly improved with an increasing Zr concentration. The time to reach 90% of the maximum hydrogen storage capacity decreased to 2946 s, 230 s, and 120 s, respectively, with the increases in Zr concentration. The initial hydrogen absorption content of the alloys increased and then decreased after the addition of the element Zr. The second phase expanded with an increasing Zr concentration, which in turn decreased the abundance of the BCC main phase. The Ti43V25Cr25Zr7 alloy showed good cycle stability and hydrogen-desorption performance, and it could absorb 90% of the maximum hydrogen storage capacity in around 230 s. The maximum hydrogen-absorption capacity of the alloy was 2.7 wt%. The diffusion activation energy of hydrogen desorption dropped from 102.67 kJ/mol to 92.62 kJ/mol. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the impact of high velocity oxy-fuel (HVOF) spraying parameters on the inflight particle temperature, velocity, and microstructure of FeCrMnCoNi high-entropy coatings (HECs). The sprayed coatings exhibited a typical lamellar structure with a single solid solution FCC phase and minor oxides. Ex-situ characterization of the coatings was conducted using X-ray diffraction, Raman spectroscopy, and high-resolution scanning electron microscope (HR-SEM) to analyze the phase composition, microstructure, and surface morphology. The findings revealed that fuel-rich flames with a higher feed rate resulted in coatings with low porosity and oxidation as well as high deposition efficiency due to the high velocity and low particle temperatures. Additionally, the transverse scratch tests were conducted to determine the cohesive/adhesive nature of the coatings, and the results demonstrated that the cohesive strength between the splats was influenced by the porosity and area fraction of the oxides. Coatings deposited with oxygen-rich conditions showed maximum hardness, but low cohesive strength compared to coatings sprayed using fuel-rich conditions due to higher oxides formation during spraying. The microstructural changes, phase compositions, and microhardness of the coatings were correlated with the scratch resistance of the HECs developed using three distinct spraying conditions. These results suggest that FeCrMnCoNi HECs hold significant potential for surface protection in various industrial and aerospace applications. Moreover, the findings point toward new material design strategies to attain desired microstructure with enhanced mechanical properties. [ABSTRACT FROM AUTHOR]

In the present paper, microstructural changes in two alloys, IN617 and DMV617 mod, after 5 h and 1000 h of aging at 700 °C were investigated using scanning transmission electron microscopy. The mechanical properties of the samples were evaluated using hardness tests. Precipitates were identified using energy-dispersive X-ray spectroscopy analysis. After long-term aging, intensive precipitation of the M23C6 carbides and γ′ intermetallic phase in the microstructure of alloys was observed. In the IN617 alloy, continuous layers of M23C6 carbides along the grain boundaries after long-term aging were observed. The minor addition of boron to the DMV617 mod alloy is advantageous in microstructure formation during long-term aging because it decreases the agglomeration of M23C6 at the grain boundaries. [ABSTRACT FROM AUTHOR]

Aeolian sand and loess are both natural materials with poor engineering-related properties, and no research has been devoted to exploring aeolian sand–loess composite materials. In this study, we used aeolian sand and loess as the main raw materials to prepare unfired bricks by using the pressing method, along with cement, fly ash, and polypropylene fiber. The effects of different preparation conditions on the physical properties of the unfired bricks were investigated based on compressive strength, water absorption, and softening tests and a freeze–thaw cycle test combined with X-ray diffraction and scanning electron microscope analysis to determine the optimal mixing ratio for unfired bricks, and finally, the effects of fibers on the durability of the unfired bricks were investigated. The results reveal that the optimal mixing ratio of the masses of aeolian sand–loess –cement –fly ash–polypropylene fiber–alkali activator–water was 56.10:28.05:9.17:2.40:0.4:0.003:4.24 under a forming pressure of 20 MPa. The composite unfired bricks prepared had a compressive strength of 14.5 MPa at 14 d, with a rate of water absorption of 8.8%, coefficient of softening of 0.92, and rates of the losses of frozen strength and mass of 15.93% and 1.06%, respectively, where these satisfied the requirements of environmentally protective bricks with strength grades of MU10–MU15. During the curing process, silicate and sodium silicate gels tightly connected the particles of aeolian sand and the loess skeleton, and the spatial network formed by the addition of the fibers inhibited the deformation of soil and improved the strength of the unfired bricks. [ABSTRACT FROM AUTHOR]

The stability and dispersion of Copper (Cu) powders in an aqueous medium impacts their performances. Thus the Cu powder suspensions were prepared by adding different stabilizers—sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), polyvinyl pyrrolidone (PVP), and hexadecyl trimethyl ammonium bromide (CTAB); the best surfactant was selected and its stability and dispersion were studied. The study systematically examined the effect of the stability of suspensions via sedimentation analysis, including solid–liquid ratio, the concentration of stabilizer, and dispersion time. The particle size, the stability of suspensions, phase composition, and microstructure of Cu powders were characterized by laser particle size analyzer, zeta potential, X-ray diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscope (SEM). The results indicate that the stability of the suspension is improved with the addition of PVP due to the steric hindrance of PVP, and the growth and agglomeration of particles are retarded by the formation of a thick hydration layer with the optimizing concentrations, dispersion time, and solid–liquid ratio 10 g/L, 30 min, and 1:25, respectively. [ABSTRACT FROM AUTHOR]

Numerous studies focus on investigating organic soils with high organic content. However, only a limited amount of literature discusses the properties and behaviour of low organic content soils. Sri Lankan organic soil is an excellent example of a low organic content soil, demonstrating different behaviour from highly organic fibrous soil. Scanning electron microscope (SEM) images of Sri Lankan organic soil were studied to determine the reasons for these observed variations. Sri Lankan organic soils were observed to consist of highly decomposed organic matter in an amorphous state with higher proportions of mineral matter. The microstructure characteristics observed through SEM images mostly explained the variation of properties and behaviour of the Sri Lankan organic soil in contrast to highly organic fibrous soil. Correlations were also derived between properties of Sri Lankan organic soil and compared with similar relationships derived from other geological conditions. While some correlations derived in this study closely follow the relationships for other organic soils with similar microstructure characteristics, the acidity of the deposit resulted in different behaviour of a few correlations. This study improves the current knowledge of the effect of microstructure characteristics on the properties and behaviour of Sri Lankan low-organic clayey soils, which otherwise primarily depend on theories for highly organic peaty soils. Furthermore, the correlations derived and validated for low organic soils can be utilized in any organic clay deposit with similar microstructure characteristics. [ABSTRACT FROM AUTHOR]

Using BNi as the interlayer material, transient liquid phase diffusion welding experiments were conducted on Q355 steel at a welding temperature of 1050 °C under different holding times (10, 15, 20, 25 min). The welded joint microstructure, element diffusion migration, and phase composition were analyzed by using modern analytical testing instruments such as optical microscope (OM), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The mechanical properties of the joint were tested and analyzed by using a microhardness tester, universal testing machine, and impact testing machine. The electrochemical corrosion property of the welded joint was analyzed and studied by using an electrochemical workstation. The results showed that under the conditions of 1050 °C and 6 MPa pressure, the Q355 steel TLP welded joint with better property could be obtained with a 20-min holding time. With the increase of holding time, the width of the bonding interface layer increased first and then decreased, and the microstructure tended to be more uniform. The shear strength gradually increased, reaching a maximum of 496.7 MPa (25 min), but the impact toughness increased first and then decreased, with a maximum of 250.61 J/cm2 (20 min). The corrosion resistance of the joint also improved first and then weakened. [ABSTRACT FROM AUTHOR]

Soil heavy metal pollution poses a formidable challenge for environmental protection professionals. This study delves into the impact of zinc and lead pollution on the particle size distribution, liquid-plastic limit, permeability, shear strength, and other pertinent physical and engineering properties of clay. The alterations in the microstructure of soil contaminated by heavy metals were scrutinized using a scanning electron microscope. The findings reveal that as the concentration of heavy metals in contaminated soil rises, there is a concurrent decrease in the liquid limit, plasticity index, and silt content. This, in turn, leads to the deterioration of the original fluidity and plasticity of the soil, accompanied by a reduction in fine particles. Resistivity tests indicate that an escalation in water content results in a decrease in resistivity, an increase in porosity leads to an increase in resistivity, and an elevation in the concentration of heavy metals precipitates a sharp decline in resistivity due to the heightened conductivity of heavy metal ions. Heavy metal pollution induces structural changes in the soil, particularly in pore size, thereby influencing the permeability coefficient. [ABSTRACT FROM AUTHOR]

Magnesium alloys are very interesting engineering materials because of their high strength-to-density ratio. On the other hand, they are characterized by low hardness as well as low erosion resistance. Because of these reasons, their applications in the industry are very limited. The article presents the results of the high velocity oxy-fuel (HVOF) spraying of the hard cermet coatings onto AZ31 magnesium alloy substrate. Three feedstock powders were used in the process with composition (wt.%): WC-12Co, WC-10Co-4Cr and WC-20Cr3C2Ni. The spray distance (SD) was selected as a variable parameter with values equal to 320 and 400 mm. Observations carried out under a scanning electron microscope (SEM) revealed a typical HVOF-sprayed microstructure with a compact structure and low porosity (below 3 vol.%). The hardness of the manufactured coatings, ranging from 912 HV0.2 to 1328 HV0.2, what was significantly higher than the substrate. The solid particle erosion tests were carried out according to the ASTM G76-04 standard. Erosive experiments were done for 30°, 60° and 90° inclination angles of the nozzle using Al2O3 abrasive. Erosion tests confirm that cermets exhibit substantial erosion resistance better than the substrate. The highest erosion resistance was noted for WC-10Co-4Cr coatings. The erosion rate for cermet coatings was mostly below 0.9 mg/min, whereas for the AZ31 it was more than 1.5 mg/min. In the case of the average erosion value, it was between 12 and 22 times lower than for the substrate. Results analysis reveal that shorter spray distance decreases porosity, increases hardness, and finally supports erosion resistance of the cermets. [ABSTRACT FROM AUTHOR]

The effect of aging treatments at various temperatures on the mechanical properties and microstructure of 10B21 cold heading steel with a 20% reduction in area (ε = 0.1) was investigated. The mechanical properties were evaluated based on tensile tests and hardness tests, while the evolution of microstructure was observed by using an optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results reveal that aging treatment enhance the strength and hardness of 10B21 cold heading steel after drawing, and the highest values of strength and hardness are attained at an aging temperature of 300 °C. Specifically, the yield and ultrahigh tensile strength after aging at 300 °C are measured at 620 MPa and 685 MPa, respectively, which are 30 MPa and 50 MPa higher than the cold-drawn sample. Moreover, the hardness after aging at 300 °C reaches 293 HV, which has an increase of 30 HV compared to the cold-drawn state. The improvement in mechanical properties may be related to the strain-aging mechanism and the increased density of dislocations. In addition, the analysis of the TEM results reveal that the presence of the second-phase Ti(C,N) contributes to pinning the dislocations, whereas the dislocations are pinned between the cementite (Fe3C) lamellar and stacked at the grain boundaries, leading to strain hardening of the material. [ABSTRACT FROM AUTHOR]

Developing novel solid oxide fuel cells (SOFCs) with high stability running at low temperatures is an important objective in SOFC science. In the current paper, a comprehensive physics-based microstructure modeling using scanning electron microscope (SEM) image analysis was performed on several anode-support SOFCs operating at low temperatures with high stability. To bridge the gap in the literature regarding an accurate and realistic modeling, a new model was developed based on the variable fuel and air utilization factors and updated microstructure values (e.g., tortuosity, porosity, pore size, grain size). The model accuracy was verified by a thorough point-to-point validation for eight different cells with the configuration of Ni-YSZ (anode), YSZ (electrolyte), and GDC/PNO (cathode). Different temperatures, hydrogen, and air mass flow rates were used, for which an average error of less than 3% in the I-V curves was achieved. The microstructure of the cells, including cathode thickness (15–26 μm), anode-support thickness (350–460 μm), porosity (39 and 43%), grain size (1.1–1.4 μm), and pore radius (0.9–1.1 μm) were varied. Moreover, the effects of the critical operational and design parameters on the overpotential losses and cell performance were studied. The results show that a hydrogen flow rate of 43 sccm was ideal when the cell operated at 0.9 A/cm2 and 700 °C. Moreover, an average anode-support pore radius of 1.75 μm resulted in the best cell performance. It was also concluded that the electrolyte thickness has a higher effect on the cell performance compared to the cathode thickness. • Fabrication and testing of eight anode-supported tublar cells with different microstructures. • Introducing a physics-based microstructure model for SOFC based on variable fuel utilization factor. • Performing a comprehensive SEM image analysis for the fabricated cells. • Achieving an average error of less than 3% for the model compared to the experimental data. • Achieving an average optimum value of 1.75 μm for anode-support pore radius. [ABSTRACT FROM AUTHOR]

The disposal of industrial by-product tailings has become the focus of mine follow-up work and an important issue in solving environmental pollution. This study explores the potential of utilizing iron tailings and phosphogypsum as cementitious materials, guided by the concept of comprehensive utilization. The mechanical property of cementitious materials was studied under curing 7 days, 14 days, and 28 days. The characteristics of the pores and products of the cementitious material were extracted and analyzed by industrial computed tomography (CT), X-ray diffraction (XRD), and scanning electron microscope (SEM). In the presence of phosphogypsum, more ettringite was generated in the cementitious system. The macropores in the system were filled, reducing the total porosity fraction of cementitious materials from 24.56% to 18.39%. The reduction of macropores significantly enhanced the compressive strength of cementitious material. The addition of fine phosphogypsum reduced the large porosity of the cementitious materials, which revealed the importance of the size in the cementitious material system. The effect of phosphogypsum content on the pore structure of cementitious material of iron tailings was studied. The new type of low-carbon cementitious material prepared from phosphogypsum and iron tailings provided a novel perspective for the multi-solid waste collaborative disposal in this study. In addition, the large amount of consumption of tailings reduced the pollution to the environment. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to identify the optimal forming angle for the selective laser melting (SLM) process and evaluate the mechanical properties of the SLM-formed GH3536 alloy in the aero-engine field. Design/methodology/approach: Forming the samples with optimized parameters and analyzing the microstructure and properties of the block samples in different forming angles with scanning electron microscope, XRD, etc. so as to analyze and reveal the laws and mechanism of the block samples in different forming angles by SLM. Findings: There are few cracks on the construction surface of SLM formed samples, and the microstructure shows columnar subgrains and cellular subgrains. The segregation of metal elements was not observed in the microstructure. The pattern shows strong texture strength on the (111) crystal plane. In the sample, the tensile strength of 60° sample is the highest, the plasticity of 90° forming sample is the best, the comprehensive property of 45° sample is the best and the fracture mode is plastic fracture. The comprehensive performance of the part is the best under the forming angle of 45°. To ensure the part size, performance and support structure processing, additional dimensions are added to the part structure. Originality/value: In this paper, how to make samples with different forming angles is described. Combined with the standard of forged GH3536 alloy, the microstructure and properties of the samples are analyzed, and the optimal forming angle is obtained. [ABSTRACT FROM AUTHOR]

In this study, basalt fibers (BFs) and nano-silica (NS) were innovatively combined to reinforce recycled aggregate concrete (RAC) to prepare recycled aggregate concrete (named NBRAC) with better mechanical and microstructural properties as an alternative to ordinary concrete. Different NBRAC specimens were prepared by adjusting the contents of NS and BF; the damage mechanism and mechanical properties of NBRAC were investigated; and the compressive, split tensile, and flexural strengths of NBRAC were evaluated. The microstructure of NBRAC was analyzed by scanning electron microscopy observation. The results showed that the densification of NBRAC was improved under the condition of 50% RA substitution rate and that its compressive, split tensile, and flexural strengths were increased by 6.8%, 16.3%, and 32.7%, respectively, compared with that of natural concrete, which proved that the method was feasible for the preparation of high-performance RAC. Scanning electron microscope image analysis confirmed the improvement effects of NS and BF on RAC, and combined with the experimental data, a composite explanation for the improvement effects of NS and BF on RAC was proposed for the first time. [ABSTRACT FROM AUTHOR]

The effect of angle between growth-ring orientation and loading force on mechanical performance such as compressive strength, deformation and compression set-recovery of wood has not been fully understood. The specimens, with growth-ring orientations of 0° (G-0°, parallel to tangential direction), 15° (G-15°, angle between growth-ring and tangential direction) and 40° (G-40°), were compressed using a universal testing machine; meanwhile, strain distribution was recorded using digital image correlation (DIC). One specimen from each growth-ring orientation was scanned with X-ray computed tomography (X-ray CT) before and after compression test. Their micro-structure after compression test was imaged using a scanning electron microscope (SEM). The results show that compressive strength decreases and compression set-recovery increases as increasing the growth-ring orientation. In G-0° specimens, strain is easily accumulated in small regions in earlywood, resulting in structural compaction and collapse. The effect of latewood on compressive strength is small, resulting in a poor correlation between strain distribution and density profile. For G-40° specimens, strain is almost homogenously distributed in every layer of earlywood. Both earlywood and latewood restrain the specimen from deformation and failure. Hence, strain accumulates according to the 'layers' of earlywood. Strain distribution and structural changes in G-15° specimens were in between of G-0° and G-40° specimens. [ABSTRACT FROM AUTHOR]

The microstructure characteristics of rocks are the internal basic properties of fine-grained rocks, which affect their physicochemical behavior. This paper takes an example as fine-grained grains in the Yanchang Formation 7 Member of Ordos Basin. First, the geometric morphology characteristics of fine-grained grains are analyzed quantitatively by field scanning electron microscope and image recognition technology. Then, we characterized the influence of the sedimentary environment on the geometric shape and orientation arrangement of fine-grained grains. Results show that the grains in the deep-semi-deep lacustrine facies take the characteristics of fine grain size (2-3 μm), flat and angular shape. The grains are directionally distributed along with a continuous interval. The intensity of the distribution shows a flat quasi-cone shape and well-directional orientation. The fine grains in shallow lake facies are medium-fine grains (2-8 μm), flat and angular type. Besides, the grains show a sharp distribution a-long with a certain interval with no obvious regularity, which has a moderate orientation arrangement. The fine grains in delta facies are fine-grained (8-12 μm) and quasi-circular type. This type of fine-grained rock has an irregular distribution. The intensity distribution of fine grains is circular or elliptical. The circumferential angularity index and flatness of grains can promote the formation of oriented arrangement structure of grains. By contrast, the anisotropy rate and grain size are unfavorable for the formation of an oriented structure. The results are helpful to understand the microstructural characteristics of fine-grained rocks and establish the relationship between microstructures and macrostructures of rocks. [ABSTRACT FROM AUTHOR]

Calcium sulfoaluminate (CSA) cement, as a type of low-carbon cement, can contribute to further reduction in carbon emissions with carbonation technologies. However, the detailed microstructure development of CSA cement during the carbonation process has been rarely analyzed. In this paper, wet carbonation was applied to CSA cement to investigate the microstructure evolution of carbonation products and carbon absorption capacity of CSA cement by means of pH measurement, X-ray diffraction (XRD) measurement, thermogravimetric (TG) measurement, Fourier-transformed infrared spectroscopy (FT-IR) measurement and scanning electron microscope measurement. During the carbonation process, the formed ettringite product and the dicalcium silicate clinker were carbonated immediately to generate calcium carbonate crystals, silica gel and aluminum hydroxide (AH3) gel. With the trend of pH increasing first and notably decreasing later, the coupling interaction between the hydration and carbonation reactions of CSA cement was revealed. From the XRD and TG results, three types of calcium carbonate crystal forms (calcite, vaterite and aragonite) were detected, and the content of calcium carbonate increased with the increase in carbonation time. FT-IR analysis further confirmed the existence of calcium carbonate, silica gel and AH3 gel with their characteristic vibrations. Moreover, the microstructure of carbonation products with different morphologies was observed. The application of wet carbonation to CSA cement provides a more comprehensive insight to the carbonation mechanism of this low-carbon cement. [ABSTRACT FROM AUTHOR]

The effects of alloying elements on the microstructure evolution and properties of GH2107 superalloy during long-term aging are investigated by optical microscope, scanning electron microscope, and transmission electron microscope. The results indicate that the microstructure of the alloy becomes unstable with the prolongation of aging time. Cr element promotes the precipitation of M23C6 carbides at grain boundaries, and Fe element inhibits the precipitation and growth of M23C6 carbides at high temperature. At the same time, high Fe promotes the growth of γ' phase and the precipitation of TCP phase, which has a certain influence on the plasticity and strength of the alloy. The yield strength of alloy1 (15.41% Cr, 35.3% Fe) and alloy2 (15.08% Cr, 40.1% Fe) decreases with the increase in aging time. However, for alloy3 with high Fe content, the yield strength increases suddenly at 3000 h aging time due to the improving effect of solid solution strengthening. In addition, the dislocation movement mechanism of GH2107 alloy was studied, and Orowan bypass mechanism is more likely to occur in alloys with high Fe content. [ABSTRACT FROM AUTHOR]

The stability of microstructure and performance after long-term service are crucial for the engineering application of ASME SA335-P92 steel. In this present work, a series of isothermal aging tests for P92 steel were performed at 680 °C as long as 21,000 h. Microstructure at different stages of evolution was characterized using scanning electron microscope and transmission electron microscopy. Strength and plasticity measurements under the static mechanical tensile condition were also carried out at room temperature. Results showed that Laves phases precipitated rapidly at the early aging stage and coarsened with a relatively high rate in the followed aging period, while M23C6 carbides were precipitated continuously during the aging process. The tensile strength and plasticity of P92 steel at room temperature declined rapidly at the early stage of aging. During the afterward aging process, strength overall presented a slowly falling tendency but plasticity remained a sustainable stability. Micro-mechanism of variation on mechanical tensile properties for P92 steel aged for a long-term time would be further revealed in this paper. [ABSTRACT FROM AUTHOR]

In this work, the effect of Mo on the microstructure and properties of Ni-Mo-Al2O3 coatings by cold spraying was studied. The microstructure, composition, hardness, wear resistance and chlorine salt corrosion resistance of the coatings were analyzed by a scanning electron microscope, EDS, X-ray diffractometer, 3D profilometer, microhardness tester and friction wear tester. The results show that the coatings have low porosity and a uniform structure. The addition of Mo can improve the hardness, electrical conductivity, wear resistance and chlorine salt corrosion resistance of the coating but reduce the deposition efficiency of the powder. In general, the 80Ni-10Mo-10Al2O3 coating has the best comprehensive performance, with a hardness of 270.17 HV, friction coefficient of 0.4171 and corrosion rate of 0.287 g/m2·h in molten chloride. [ABSTRACT FROM AUTHOR]

Foamed concrete, which has excellent performance, has been gradually used to enhance the thermal insulation performance of buildings in recent years. However, there are few studies on the durability of foamed concrete under environmental action. In order to understand the law of damage and deterioration of foamed concrete under dry-wet cycles in acidic environment, the standard sample of foamed concrete was first pre-treated with different times of dry-wet cycles under neutral and two acidic environments, then quality inspection, uniaxial compression test and scanning electron microscope were carried out on the treated foamed concrete by electronic scale, universal testing machine and electron microscope. Accordingly, the deterioration effect and deterioration mechanism of foamed concrete under dry-wet cycles in acidic environment is analyzed. The results show that the quality and uniaxial compressive strength of foamed concrete decrease gradually with the increase of the number of dry-wet cycles in both neutral and two acidic environments; the stronger the acidity of dry-wet cycles, the more the quality of foamed concrete decreases and the more obvious the deterioration effect of uniaxial compressive strength of foamed concrete; the acidic dry-wet cycles will corrode the foamed concrete, resulting in the expansion and consolidation of pores and the appearance of cracks, and the more the number of dry-wet cycles, the more obvious the corrosion effect of the foamed concrete. The research results can provide scientific basis for the analysis of the safety and stability of foamed concrete members under the dry-wet cycle in acidic environment. [ABSTRACT FROM AUTHOR]

The influence of milling time and volume fraction of reinforcement on the morphology, microstructure, and mechanical behaviors of SiCp-reinforced AA2017 composite powder produced by high-energy ball milling (HEBM) was investigated. AA2017 + SiCp composite powder with different amounts of SiC particles (5, 10, and 15 vol%) was successfully prepared from gas-atomized AA2017 aluminum alloy powder with a particle size of <100 μm and silicon carbide (SiC) powder particles with an average particle size of <1 μm. An optical microscope (OM), X-ray diffraction (XRD), and scanning electron microscope (SEM) were utilized to characterize the microstructure of the milled composite powder at different milling periods. The results indicated that the SiC particles were homogeneously distributed in the AA2017 matrix after 5 h of HEBM time. The morphology of the particles transformed from a laminar to a nearly spherical shape, and the size of the milled powder particles reduced with increasing the content of SiC particles. The XRD analysis was carried out to characterize the phase constituents, crystallite size, and lattice strain of the composite powders at different milling periods. It was found that with increasing milling time and SiC volume fraction, the crystallite size of the aluminum alloy matrix decreased while the lattice strain increased. The average crystallite sizes were reduced from >300 nm to 68 nm, 64 nm, and 64 nm after 5 h of milling, corresponding to SiC contents of 5, 10, and 15 vol%, respectively. As a result, the lattice strain increased from 0.15% to 0.5%, which is due to significant plastic deformation during the ball milling process. XRD results showed a rapid decrease in crystallite size during the early milling phase, and the minimum grain size was achieved at a higher volume fraction of SiC particles. Microhardness tests revealed that the milling time has a greater influence on the hardness than the amount of SiC reinforcements. Therefore, the composite powder milled for 5 h showed an average microhardness three times higher than that of the unmilled powder particles. [ABSTRACT FROM AUTHOR]

The deformation aspects associated with the micro-mechanical properties of the powder laser bed fusion (P-LBF) additively manufactured stainless steel 316L were investigated in the present work. Toward that, micro-pillars were fabricated on different planes of the stainless steel 316L specimen with respect to build direction, and an in situ compression was carried out inside the chamber of the scanning electron microscope (SEM). The results were compared against the compositionally similar stainless steel 316L, which was fabricated by a conventional method, that is, casting. The post-deformed micro-pillars on the both materials were examined by electron microscopy. The P-LBF processed steel exhibits equiaxed as well as elongated grains of different orientation with the characteristics of the melt-pool type arrangements. In contrast, the cast alloy shows typical circular-type grains in the presence of micro-twins. The yield stress and ultimate compressive stress of P-LBF fabricated steel were about 431.02 ± 15.51 − 474.44 ± 23.49 MPa and 547.78 ± 29.58 − 682.59 ± 21.59 MPa, respectively. Whereas for the cast alloy, it was about 322.38 ± 19.78 MPa and 477.11 ± 25.31 MPa, respectively. Thus, the outcome of this study signifies that the AM-processed samples possess higher mechanical properties than conventionally processed alloy of similar composition. Irrespective of the processing method, both specimens exhibit ductile-type deformation, which is typical for metallic alloys. [ABSTRACT FROM AUTHOR]

Dynamic compaction is a common foundation treatment method for loess and it is significant to understand the mechanical behavior of loess after compaction for engineering construction in loess areas. To gain insight into the variation of mechanical properties and microscopic mechanisms of loess under different compaction conditions, a series of indoor tests including particle size analysis, oedometer test, unconfined compressive strength test and scanning electron microscope imaging were carried out using intact and compacted loess in the compaction field as test materials. The results show that the ameliorative effects of dynamic compaction on the compressibility, collapsibility, and compressive strength of loess decline with increasing soil depth. Furthermore, the mechanical behaviors of loess at the compaction point are more pronounced than that of the loess between compaction points. Although increasing the ramming energy can improve the reinforcement effect, it does not change the spatial variability of the engineering properties of compacted loess with depth, compaction point and inter- compaction location. During the compaction process, the directional distribution of pores is weakened and the morphological complexity is increased as the macropores within the loess change to mesopores and then to small pores and micropores. The sequence of evolution for the loess structure is overhead-mosaic-flocculent with an increase in compactness. In addition, the clay content and nonuniformity coefficient are all positively correlated with the mechanical properties. These discoveries help better cognition of the reinforcement process for Malan loess subjected to dynamic compaction, as well as the stability study of loess foundations. [ABSTRACT FROM AUTHOR]

Copper-clad aluminum wires have a high risk of electrical fire, and welding marks are easily affected by factors such as high temperature and fire water in the actual fire. To accurately identify the overcurrent fault, an electrical fault simulator was used in this study to simulate the overcurrent fault condition of a copper-clad aluminum at a current of 52.5–105 A. Then the microstructure characteristics such as metallographic structure, welding hole elements, and so on under different treatment methods were also analyzed using the metallographic microscope and SEM/EDS. The results of the study are summarized as follows: (1) under the method of natural cooling, the metallographic structure of the welding mark were mainly columnar crystals and dendritic crystals with a few holes in it. And we found that the maximum particle size and average particle size have a quadratic function relationship with the current value; (2) under the water-cooling method, the welding mark was mainly columnar crystals with a large number of holes in them. At a current of 75 A, the welding mark holes consisted of Al and Cu elements, while at the rest of the current value, they consisted of Al, Cu, and O elements; (3) when the temperature was raised to 450 °C, the welding trace has different elements at different currents. At the temperature of 650 °C, a large number of equiaxed crystals appeared in the welding trace, with a few holes in which at a current at 105 A only. Our study has provided a basis for the investigation of electrical fire accidents and the technical identification of the causes. [ABSTRACT FROM AUTHOR]

This study investigated the effect of the Cr limits on the microstructure and mechanical properties of 316L alloy. Five 316L alloys with varying Cr contents (16.8, 17.1, 17.3, 17.8 and 18.8 wt.%) were produced by the powder metallurgy (P/M) method. Microstructure studies and phase analysis were performed with a scanning electron microscope (SEM), optical microscopy (OM), and energy dispersive spectrometry (EDS). Tensile tests and hardness measurements were performed to evaluate the hardness, strength, and ductility of the alloys. The results showed that Cr addition affected the porosity and grain size of the alloys, as well as the formation of precipitates. The ultimate tensile strength reached a maximum at 17.3 wt.% Cr and then decreased with further Cr addition. Ductility decreased with increasing Cr under the influence of precipitates formed and changes in microstructure. On the other hand, the hardness increased with increasing Cr inversely to the ductility. [ABSTRACT FROM AUTHOR]

In this study, the effect of increasing exposure time on the microstructures, porosity, mechanical properties and corrosion behavior of selective laser melted sample Al-Si10-Mg powder was investigated. The samples were processed at the same power (375 W) and scan speed (2000 mm/s), but with increasing exposure time. Exposure time equal to 40, 50 and 60 µs was applied. The features of the analyzed samples show that with increasing exposure time, greater efficiency of the heat input was obtained, with a larger size of the melt pool and Si particles and lower porosity. Specifically, at the highest exposure time the melt pool showed an increase of 19% in width and 48% in depth, while the volume percentage of the voids decreased by 50% with respect to the lowest exposure time. Moreover, with the coarser microstructure being associated with a lower level of voids, the average hardness is similar for the analyzed samples. Corrosion resistance was evaluated, being one of the most important properties that may affect the service performance of Al-Si10-Mg alloy in the aerospace, marine and automotive industries. The potentiodynamic curves of the samples show that the voids occurrence is more significant with respect to the scale of the microstructure on corrosion behavior, with the sample processed at the highest exposure time being the more resistant to corrosion. The experimental techniques used in the present study were Optical Microscope (OM), Scanning Electron Microscope (SEM), hardness and X-Ray Computed Tomography. [ABSTRACT FROM AUTHOR]

The hot tensile behavior of an extruded 6082 alloy sheet at varying temperatures and strain rates was investigated by a Gleeble3500 thermal simulation testing machine. The optical microscope (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were applied to observe the microstructure evolution. It is found that the flow stress of the studied alloy declines with increasing deformation temperature. When deformed at high temperatures, the density of dislocation decreases obviously. In addition, precipitate coarsening occurs, resulting in a decrease in deformation resistance. The dimple number of the fracture samples increases with temperature and the size of the dimple becomes deeper, exhibiting an excellent plasticity. The 6082 sheet presents anisotropy of mechanical behavior at 300 °C, this can be attributed to the fibrous grain and the Brass component {011}<211>. The anisotropic behavior seems to be slighter with an increase in temperature. No obvious anisotropic behavior was found when tensiled at 400 °C. Because it is easier to activate the slip system at elevated temperatures, meanwhile, the recrystallization begins to occur at 400 °C. [ABSTRACT FROM AUTHOR]

The hurry for ecological practices and waste control has emerged as an obligation in modern times, demanding precise strategies to restrain waste accumulation and to stimulate recycling and reuse actions to lower the climate effect. The replacement of binary raw materials for porcelain chamotte waste in siliceous porcelain was studied to obtain eco-friendly high-voltage porcelain. Quartz and feldspar were progressively replaced by 5, 10, and 15 wt.% of porcelain chamotte in a conventional siliceous electro-technical porcelain composition. The replacement effect on sintered samples at 1250°C under industrial heat treatment was evaluated by measuring the linear shrinkage, bulk density, porosity, flexural strength, and microhardness technological properties. Phase analysis was carried out by X-ray diffraction. Microstructural characteristics were studied using a scanning electron microscope. The results showed that chamottecontaining samples reached bulk densities of about 2.36 g/cm3 and a porosity percentage near zero. The maximum flexural strength value at glazed states was 87.8 MPa, for 15 wt.% scrap-containing samples. X-ray diffraction studies revealed a higher mullite phase content in chamotte-containing samples. Scanning electronic microscopy images of the polished and etched specimens show the presence of quartz grains and secondary mullite needles embedded in a feldspathic vitreous matrix. The properties reached by the chamottecontaining samples are attractive since the values obtained in terms of flexural strength, density, and porosity are compared to those reported for conventional siliceous porcelain were obtained. The most noticeable result was observed in flexural resistance. The glazed porcelain bodies showed a flexural strength improvement of about 15%. Then, these porcelain compositions suggest an alternative to produce a more sustainable, affordable, and environmentallyfriendly porcelain insulator product. [ABSTRACT FROM AUTHOR]

Featured Application: Mechanical properties and penetration characteristics of mudstone slag-based waterproof composites under cyclic loading. In this study, ground polymers were prepared from mudstone and slag. NaOH and water glass were used as alkaline exciters and mine waste rock aggregate was used as the aggregate for mudstone slag-based waterproof composites (MSWCs). A series of laboratory tests, including a uniaxial compression test, uniaxial cyclic loading and unloading test, scanning electron microscope test, and rock penetration test were conducted for macrostructural and microstructural analysis. The effect of the coupling between the mudstone proportion and the number of uniaxial cyclic loading and unloading tests was investigated. The results showed that it is feasible to use mudstone and slag to synthesize geopolymers, and that MSWCs fulfil the conditions for use as a reconstituted water barrier. The permeability of MSWCs with the different mudstone proportions set in this study fulfils the requirement of being used as a material, and the permeability and uniaxial compressive strength of the MSWCs gradually decreased with increases in the mudstone proportion. Considering the UCS and permeability of the MSWCs, the optimal mudstone proportion of the MSWC is r = 0.6. In this test, cyclic loading and unloading times of 0, 25, 50, and 100 were set, and with an increase of cyclic loading and unloading times, the UCS of the MSWCs showed a tendency of increasing first and then decreasing. In the SEM test, with an increase of cyclic loading and unloading times, microfractures and pores appeared in the MSWCs, which led to a gradual increase in its permeability and a decrease in its waterproofness. [ABSTRACT FROM AUTHOR]

The effect of finishing rolling reduction on microstructures and textures of grain oriented silicon steel was researched by optical microscopy, zeiss ultra 55 Scanning Electron Microscope (SEM) and Electron Backscatter Diffraction (EBSD) technique severally. The results show that the grain size of hot rolled sheets and decarburized strips decreases, while the center grain size of the normalized sheet increases with the increase of the finishing rolling reduction. The pearlite content increases with the increase of the finishing rolling reduction after normalization. Compare with the previous research, the effect of finishing rolling reduction on the grain size of primary recrystal-lization is greater than that of roughing rolling reduction, and large rolling reduction is beneficial to the formation of {110}<001> texture. [ABSTRACT FROM AUTHOR]

In wholemeal bread production, scalding and fermentation contribute to the improvement of the structural characteristics of the dough and bread. The influence of fermented scald on rye and barley dough and bread structure formation was specified in this study. The microstructural analysis performed using a scanning electron microscope revealed the separation of phases during the fermentation of scalds. According to the storage G′ and loss G″ moduli, both scalds exhibited elastic character over viscous. The fermentation of barley scald increased both moduli and complex viscosity, while no substantial changes were observed in the fermented rye scald. The addition of fermented scald containing partially hydrolyzed starch and a fraction of water-soluble compounds contributed positively to the formation of a well-organized structure of dough fermented for 4 h. Fermentation substantially reduced the dough's complex viscosity and moduli values, confirming the partial structure alteration leading to the viscous portion increase. The dough with fermented scald showed a significantly lower loss factor than the dough without fermented scald, indicating enhanced mechanical process ability. The most substantial weakening of the structure was observed for dough without scald. The addition of rye scald to the rye dough promoted the formation of fewer pores with relatively smaller specific volumes. [ABSTRACT FROM AUTHOR]

The excellent strain hardening behavior of high-manganese steel (HMnS) makes it widely used under strong impact and heavy wear conditions. However, the rapid hardening ability of HMnS needs to be improved under low stress. In this paper, laser remelting technology (LRT) was proposed to improve the hardening ability of HMnS under low stress. Firstly, the surface of HMnS was treated by LRT, and its surface and internal microstructure were characterized by a 3D profiler, an x-ray diffractometer, a scanning electron microscope (SEM) and an energy-dispersive spectrometer. Then, the microhardness and wear test were carried out by using a Vickers hardness tester and a wear tester, and the sub-surface microstructure and surface wear scars were tested by SEM and 3D profiler to study the wear performance of HMnS before and after laser remelting. Finally, the hardening effects and wear mechanism of laser-remelted high-manganese steel (LR-HMnS) were revealed. It was found that heterogeneities of LR-HMnS were composed of columnar structures, equiaxed structures and segregation region. These heterogeneities were conducive to improving the hardening ability of HMnS under low stress conditions, which could improve its wear resistance. [ABSTRACT FROM AUTHOR]

This paper examines the potential use of pegmatite and marble as additives in amalgamation with Meiganga kaolin to produce stoneware products capable to resist high temperatures as well as enhancement the mechanical characteristics. Two series of ceramic products were formulated by partly replacing kaolin with 0, 3, 5 and 7 wt% of both pegmatite and marble wastes. The specimens were sintered at 1000°C, 1050°C and 1100°C. Fired ceramic samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and the microstructure of the products was determined using an environmental scanning electron microscope and energy-dispersive X-ray spectroscopy. Also, the physico-mechanical properties were evaluated. Results divulged that, the addition of pegmatite or marble to kaolin enhances the strength of the ceramic body and act as a fluxing agent by promoting vitrification and glassy phase in clay after firing. The highest flexural strength results were observed with 7 wt% of pegmatite added at 1100 °C, with an increase - 35% compared to the control sample. High silica and alumina contents in pegmatite fill in voids, providing densification matrices. The incorporation of pegmatite allows to obtain a ceramic with better mechanical properties and energy saving as compared by the conventional ceramic. [ABSTRACT FROM AUTHOR]

Hot-dip aluminum alloy is widely used in the engineering fields. However, during the aluminum plating process, Fe inevitably enters and reaches a saturation state, which has a significant impact on the corrosion resistance and microstructure of the coating. Currently, adding Si during the hot-dip aluminum process can effectively improve the quality of the coating and inhibit the Fe-Al reaction. To understand the effect of Si content on the microstructure and electrochemical performance of Al-xSi-3.5Fe coating alloys, the microstructure and post-corrosion morphology of the alloys were analyzed using SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction). Through electrochemical tests and complete immersion corrosion experiments, the corrosion resistance of the coating alloys in 3.5 wt.% NaCl was tested and analyzed. The results show that the Al-3.5Fe coating alloy mainly comprises α-Al, Al3Fe, and Al6Fe. With the increase in Si addition, the iron-rich phase changes from Al3Fe and Al6Fe to Al8Fe2Si. When the Si content reaches 4 wt.%, the iron-rich phase is Al9Fe2Si2, and the excess Si forms the eutectic Si phase with the aluminum matrix. Through SKPFM (Scanning Kelvin Probe Force Microscopy) testing, it was determined that the electrode potentials of the alloy phases Al3Fe, Al6Fe, Al8Fe2Si, Al9Fe2Si2, and eutectic Si phase were higher than that of α-Al, acting as cathode phases to the micro-galvanic cell with the aluminum matrix, and the corrosion form of alloys was mainly galvanic corrosion. With the addition of silicon, the electrode potential of the alloy increased first and then decreased, and the corrosion resistance results were synchronous with it. When the Si content is 10 wt.%, the alloy has the lowest electrode potential and the highest electrochemical activity. [ABSTRACT FROM AUTHOR]